Floods in Southeast Asia

Credit:

Emergency food supplies being rushed to victims of the current
flooding in Southeast Asia are being planned with the help of a new type
of image from NASA's Terra spacecraft and a unique global flood
monitoring system funded by NASA.

With new composite surface images from Terra released last month,
Robert Brakenridge of Dartmouth College (Hanover, N.H.) produced maps
showing the precise locations of flooded areas along the Mekong River.
Hundreds of thousands of people have been displaced in the region by the
worst flooding since 1961. These maps are being used by United Nations
World Food Program staff to pinpoint the worst-hit areas.

"We get a dramatic increase in our mapping accuracy with the new
8-day composite images from the Moderate Resolution Imaging Spectroradiometer
(MODIS) instrument onboard Terra," says
Brakenridge. This new data product was released to the scientific
community in August by the EROS Data Center in Sioux Falls, South
Dakota, which is part of NASA's Earth Observing System Data and
Information System. Images were available from early June at the onset
of the Southeast Asia floods.

The frequent heavy cloud cover over Southeast Asia makes it difficult
to regularly see the surface and flooded areas, says Brakenridge. To
overcome this problem, eight MODIS images from consecutive days are
blended together to produce one image that combines all the cloud-free
views of the surface. This new image product provides a look at how much
floods rise or fall nearly every week.

Observations of floods in a region over successive years help
disaster relief agencies like the United Nations unequivocally identify
the largest flood events and allocate limited aid resources accordingly.

"The MODIS maps are proving really useful to us," said Mahadevan
Ramachandran, the United Nations World Food Program regional
vulnerability analysis and mapping officer in Phnom Penh, Cambodia. "In
areas like Cambodia and Laos where there are weak data collection
systems on the ground, the MODIS data will be our first-hand information
to identify the areas we need to visit and assess for ourselves."

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